1. Path Operator Task Force Recommendation
OC Meeting
July 16, 2014

2. POTF Strategy and Focus
POTF focus primarily on real-time operations, but covers the Operations Planning horizon (day-ahead through seasonal)
The POTF employed a three phased strategy for meeting the assigned JGC objectives:
Investigate the current Path operations paradigm and identify alternate approaches
Analyze the identified issues from the perspective of alternative approaches
Identify solutions and recommendations
Operations Planning horizon defined by NERC as “operating and resource plans from day‐ahead up to and including seasonal”

3. Background Planning horizon (> 1 year out)
TPL standards – system planning
Three phase rating process
Determines the maximum reliable Path transfers
Protects allocations of existing Path owners
In the planning horizon the system is being built

4. Background (continued)
Operations horizon (real-time through seasonal)
Seasonal studies
Sub-regional study group studies determine if the Path Rating is achievable for the upcoming season
Path SOL is designated as the lesser of the Path Rating or the Path limitation identified in the seasonal study
Path Operator updates Path Operating Procedures
Post-Seasonal Operations Planning and Real-time studies
Path Operator subsequently updates the Path SOL as necessary for anticipated outage conditions
Pre-defined “outage SOLs” are often used
Historical Path Operator role
Perform studies to establish Path Operational Transfer Capability (OTC)
Develop Path operating procedures
Mitigate Path OTC exceedances in real-time operations
POTF effort addresses the operations horizon (includes real-time, same-day, and Operations Planning Horizon)

5. Path Operator Historical Path Operator role:
Perform studies to establish Path Operational Transfer Capability (OTC)
Develop Path operating procedures
Mitigate Path OTC (now SOL) exceedances in real-time operations
Since the inception of the NERC Reliability standards, OTC was considered to be an SOL
Even though the NERC Reliability Standards apply to the TOP (and not the Path Operator), in practice, Paths are managed by the TOP who serves as the Path Operator. It’s just the reality of the way things are done.

6. NERC Recommendation
From the 9/13/12 Letter From Gerry Cauley (NERC CEO) to Mark Maher (WECC CEO at the time):
Role of Path Operators (ORG3)
“NERC is pleased to see that WECC is holding additional discussions to clarify the role of Path Operators, including the potential to implement contractual relationships and make use of RTCA and other tools to improve the accuracy of system operating limits. As these discussions continue NERC suggests that you also review the concept of Path Ratings and whether, as the Western Interconnection has become more highly interconnected, the Path Rating and Path Operator concept, along with the use of nomograms, still has merit for real-time operations. Other Interconnections do determine Flowgate limits for purposes of interchange scheduling, but rely more fully on RTCA for real-time operating reliability.”
NERC is questioning the Path operations paradigm overall for real-time operations…use of Path Ratings (Path SOLs) and the use of nomograms.
NERC supports the use of “paths” (or, Flowgates) for scheduling purposes, but wants the West to use of real-time tools and information for real-time reliability purposes
Flowgate is defined in the NERC Glossary of terms as:
1.) A portion of the Transmission system through which the
Interchange Distribution Calculator calculates the power
flow from Interchange Transactions.
2.) A mathematical construct, comprised of one or more
monitored transmission Facilities and optionally one or more
contingency Facilities, used to analyze the impact of power
flows upon the Bulk Electric System.

7. NERC/Industry Direction
Revised TOP/IRO standards emphasize:
Operational Planning Analyses (OPA) for assessing pre- and post-Contingency performance for next-day
Development of Operating Plans for issues identified in OPA
Real-time Assessments of actual pre- and post-Contingency state to determine if SOLs are being exceeded
Implement Operating Plans to prevent/mitigate SOL exceedance
Robust outage coordination process to ensure reliability under outage conditions
SOLs and SOL exceedance clarified in white paper – aligned with RC’s SOL Methodology and POTF recommendation
Industry direction => 1) perform prior studies in the Operations Planning horizon (next-day thru seasonal) to identify reliability risks and formulate operating plans
2) perform Real-time Assessments to determine if SOLs are exceeded (the meaning of this is clarified in the whitepaper)

8. POTF Recommendation There is a better way of doing what we do…
Improve reliability
Reduce unnecessary compliance liability
Increase utilization of transmission and generation assets
POTF recommendation described in this PowerPoint…the recommendation accomplished these three key items
We entered into this effort asking “Why do we do what we do?” and “Is there a better way?”
Improvements in technology, tools, information, and information sharing allow for more effective ways of ensuring reliability

9. What’s Driving This Recommendation?
NERC recommendation and direction
Availability of quality data, models, and real-time tools
Current Path operations paradigm
Reliability risks
Unnecessary compliance risks
Financial risks
1st bullet – Gerry Cauley letter, and TOP/IRO standards and the SOL whitepaper
2nd bullet – what has changed over the last several years? The southwest event revealed opportunities for improvement…technology, tools, information sharing have changed…SOL Methodology has changed…reliability standards are changing……processes should change with them
Bottom line - our history has served us well, but things have changed, and we can do better

10. Path Operations Paradigm
Identified Issues:
The Path SOL concept undermines the distinction between reliability limitations and commercial limitations
Allocations & Contracts
Reliability Limitations & Transfer Capability
3-Phase Rating Process
Path SOL
See speaker notes Word document

11. Path Operations Paradigm
Identified Issues (continued):
Path SOLs often do not take into consideration real-time tools and information
The Path SOL paradigm potentially disguises other critical limitations
The Path SOL paradigm results in “chasing the SOL”
The Path SOL paradigm results in unnecessary TOP and RC compliance risk
See speaker notes Word document

12. Path Operations Paradigm
Identified issues (continued):
The Path SOL paradigm pre-supposes the need for unique monitoring of all WECC Paths
The Path SOL concept is extraneous and redundant in light of the revised SOL Methodology
TOP designated as the Path Operator may have limited ability to manage Path SOL exceedances
The Path Operations paradigm prevents full utilization of transmission and generation investments
See speaker notes Word document

13. Proposed Solution – a New Paradigm
Core concept – distinguishing “SOL” from “TTC”
NERC definition of Total Transfer Capability
The amount of electric power that can be moved or transferred reliably from one area to another area of the interconnected transmission systems by way of all transmission lines (or paths) between those areas under specified system conditions.
TTC is a better fit for WECC Paths
Path SOL is a TTC value that is treated as a real-time operating limit – this is what NERC doesn’t like.
It is also the underlying driver behind the issues mentioned earlier.

14. Distinguish SOL from TTC
Path SOL
Path TTC:
Not an SOL
Respects SOLs
Respects 3-phase Rating process, commercial issues, contracts, and allocations
SOLs:
Facility Ratings
Voltage limits
Stability limits
These are observed pre- and post-Contingency
This interpretation of SOLs is consistent with the NERC SOL Whitepaper and the RC’s SOL Methodology
This break-up of the Path SOL is consistent with NERC recommendations
This approach consistent with FAC – Assessment of Transfer Capability for the Near-Term Transmission Planning Horizon:
R1.2 – the Planning Coordinator’s methodology for assessing Transfer Capability shall include a statement that the assessment “shall respect known System Operating Limits.”

15. TTCs
TTCs represent a blending of both reliability and commercial limitations on the system
Paths can be scheduled up to the TTC, but not over
TTCs can be adjusted at any time, including in real-time
TTCs are not monitored as a real-time operating parameter

16. SOLs
SOLs are pure reliability parameters – Facility Ratings, voltage limits, and stability limits observed pre- and post-Contingency
Paths do not have uniquely monitored SOLs unless they happen to be associated with a stability limit
SOL exceedance determined via Real-time Assessments of pre- and post-Contingency conditions – consistent with RC’s SOL Methodology and NERC SOL Whitepaper
SOL exceedance prevented or mitigated via implementation of Operating Plans
Currently, we “have a foot on each side of the fence”…SOLs currently are as described in bullet #1, and yet they are also Path SOLs. We are currently functioning in both the old paradigm and the new paradigm, and the two are having trouble coexisting.

17. RC’s SOL Methodology
“The ultimate task of TOPs and the RC is to continually assess and evaluate projected system conditions as Real-time approaches with the objective of ensuring acceptable system performance in Real-time.”
“In the Peak RC Area, the BES is expected to be operated such that acceptable system performance is being achieved in both the pre- and post-Contingency state, regardless of the tools TOPs have available.”
“If any of the acceptable pre- or post-Contingency system performance criteria stipulated in this Methodology are not being met, an SOL is being exceeded.”
“TOPs may use Real-time tools or rely on prior studies, provided that those studies demonstrate acceptable BES performance for the current or expected system conditions.”
2nd bullet - There is no reliability benefit in treating WECC Paths with any degree of uniqueness when the SOL Methodology already requires that the entire BES demonstrate acceptable pre- and post-Contingency performance.
3rd bullet – clarifies what it means to exceed an SOL – this is consistent with the NERC SOL Whitepaper (note – this has nothing to do with Paths or Path limits)
4th bullet – may need to rely on prior studies for certain types of limits (transient stability, reactive margin, for example)

18. POTF Recommendation
Improve reliability and utilization of generation and transmission assets by moving away from the Path SOL concept in the operations horizon, and moving towards full utilization of Real-time Assessments to ensure the transmission system is being operated within Facility Ratings, voltage limits, and stability limits in the pre- and post-Contingency state.
Rely on TOPs’ Operations Planning studies, Real-time Assessments, and operating plans to ensure system reliability, making TOP-007-WECC-1 redundant. Therefore, it can be retired, reducing unnecessary compliance risk.
Dissolve the Path Operator concept and align the Western Interconnection with the NERC functional model and respective entity responsibilities and authorities.
Speaker note for #2 – Does moving to this paradigm presuppose the need for all TOPs to have RTCA like tools prior to this new paradigm?
ANSWER: No. The RC’s SOL already requires the BES to demonstrate acceptable BES performance regardless of the tools TOPs employ. While real-time tools make the job easier and more accurate, they are not required for the new paradigm. The revised TOP standards, however make it more of a challenge to remain compliant without them.

19. Example
Flow on these four lines generally goes in the same direction – either S>N or N>S.
These lines could be considered an interface or a “Path”
Some Paths are internal to a TOP Area as shown here, or…
TOP Area “A”

20. Example …Paths can connect two TOP Areas as shown here, or…
TOP Area “A”
TOP Area “B”

21. Example …Paths can connect more than two TOP Areas as shown here.
TOP Area “A”
TOP Area “C”
TOP Area “B”

22. Example Each line has a family of Facility Ratings
Each bus has pre- and post-Contingency voltage limits
These are always SOLs
Therefore, there is no unique SOL to “establish” or “determine”…
The expectation is to operate within Facility Ratings and voltage limits (SOLs) pre- and post-Contingency.
TOP Area “A”
TOP Area “B”

23. Example
Prior transfer simulations show that at 1000 MW of N>S transfer, the loss a Facility somewhere results in another Facility hitting its emergency Facility Rating.
These transfer studies determine that 1000 MW is the amount of power that can be reliably transferred from TOP Area “A” to TOP Area “B”. By NERC definition, this is Total Transfer Capability.
TOP Area “A”
1000 MW
TOP Area “B”

24. Example Thermal/Voltage Limitations
Each Facility and each bus has its SOL
The 1000 MW maximum transfer level respects SOLs, but it is not the SOL itself.
Treating the 1000 MW as an SOL equates to using a “proxy” SOL.
The 1000 MW transfer limit is an appropriate SOL only when it is a stability limit
TOP Area “A”
1000 MW transfer capability – this is not an SOL
TOP Area “B”

25. Example 1000 MW voltage stability limit - this is an SOL (or IROL)
Stability Limitations
Transfer studies show that at 1000 MW, the nose of the P-V curve is reached and voltage collapse occurs upon the identified contingency.
The 1000 MW (less some margin) is the SOL (or IROL).
Transfer studies may have encountered thermal or voltage limitations at lower levels of transfer, but the system was further stressed to reasonably expected maximum levels to determine whether stability limits exist.
TOP Area “A”
1000 MW voltage stability limit - this is an SOL (or IROL)
Interfaces/paths have a uniquely monitored SOL only when the SOL is a stability limit.
If no stability limit is uncovered upon stressing the interface/path to reasonably expected maximum transfer levels, interface/path does not have a uniquely monitored SOL.
Facility Ratings and voltage limits are SOLs all the time. TOPs must operate within them both pre- and post-Contingency at all times.
TOP Area “B”

26. Comparison Current Paradigm Alternate Paradigm
Runs transfer analysis studies ahead of time to determine the Path SOL.
Runs transfer analysis studies ahead of time to determine the Path TTC and to determine the existence of stability limits.
Identifies the Path SOL and allocates the Path TTC among TOPs who operate Facilities on that WECC Path.
Allocates the Path TTC among TOPs who have TTC Facilities on that WECC Path.

27. Comparison (continued)
Current Paradigm
Alternate Paradigm
Monitors path flows to ensure they stay below Path SOL.
TOPs monitor Facility Ratings, voltage limits, and stability limits in the pre- and post-Contingency state. TOPs ensure acceptable system performance as per the RC SOL Methodology.
Makes adjustments to the Path SOL in response to real-time events.
Make adjustments to the Path TTC in response to real-time events.
Need to be prepared to answer the question "Will this new paradigm allow a Path to be operated above transfers that have been studied (ie. an "unstudied state"?)
ANSWER: N/A – stability issues would already be identified. Thermal and voltage issues captured by Real-time Assessments.

28. Comparison (continued)
Current Paradigm
Alternate Paradigm
Is responsible for mitigating Path SOL exceedances.
TOPs are expected to mitigate instances of unacceptable system performance by the most appropriate or effective means such as:
Internal congestion management tools, and/or
Local or wide-area operating plans, procedures, or Op Guides, and/or
Interconnection-wide congestion management tools administered by Peak RC.

29. Comparison (continued)
Current Paradigm
Alternate Paradigm
Has TOP-007-WECC-1 compliance responsibility when a Path SOL is exceeded for longer than 30 minutes.
TOP-007-WECC-1 is retired. Compliance responsibility for SOL or IROL exceedances will be monitored by NERC TOP and IRO standards at the facility and stability limit level.
TOP still required to take action without delay to mitigate the SOL exceedance, but no longer with a 30 minute compliance ceiling. RC can still direct action if it is determined that the TOP is not taking appropriate action to mitigate the SOL exceedance.

30. Comparison (continued)
Current Paradigm
Alternate Paradigm
Monitors the Path Scheduling limit as a whole to assure scheduled usage is not exceeding the Path’s Scheduling Limit. Exceeding the Path’s Scheduling Limit constitutes Violation.
TOP-007-WECC-1 is retired therefore there will not be a violation if the Schedule Limit (TTC) is exceeded. However, Path Schedule Use shall not exceed either the Path TTC values or the individual TOP’s share of TTC.

31. Comparison (continued)
Current Paradigm
Alternate Paradigm
TOPs/BAs adjust existing generation (or bring on expensive alternate generation) to get under an SOL that may be ultra-conservative and not be reflective of actual system conditions.
TOP and RC monitor for pre- and post-Contingency exceedance of Facility Ratings, bus voltage limits, and actual exceedance of stability limits. Action taken only when actual system conditions indicate a need for action.

32. Recommendation Specifics
The POTF recommends moving to the proposed paradigm as described in the white paper. Under the proposed paradigm:
SOLs and TTCs are separate and distinguished, but they work together to ensure that reliability is achieved in real-time operations.
The Path Operator Role in Operations is eliminated, but the roles and responsibilities of the Path Operator are distributed among the TOPs and the RC.
Establish a SAR to retire TOP-007-WECC-1.

33. Recommendation Specifics (continued)
Paths that are not associated with transient or voltage stability limits will not have uniquely monitored SOLs; however, they will continue to have TTCs.
Consistent with the RC’s SOL Methodology, SOLs are the Facility Ratings, voltage limits, and stability limits which are monitored pre- and post-Contingency.
TTC is the measure of maximum power transfer across a WECC Path that respects these SOLs pre- and post-Contingency. TTCs will still need to be determined through transfer analysis and prior studies.

34. Recommendation Specifics (continued)
Nomograms can be used to determine TTCs and can provide guidance to operators as part of operating plans, but the nomogram itself may not be an SOL.
The WECC Path Rating Catalog will continue, and the WECC Path Rating Process remains unchanged; however, the resulting Path Rating will serve as a maximum TTC value – not as an SOL.
Bullet #7 – if the nomogram defines a region of stability, the nomogram may be an SOL. If the nomogram is not stability related, it is not an SOL.
Bullet #8 – TOP/BA may choose to operate within the Path Rating, but actions taken are not due to reliability constraints if real-time assessments don’t indicate SOL exceedance.

35. POTF Recommendation
The POTF believes that implementing these eight recommendations will improve reliability, decrease unnecessary compliance exposure, and better utilize transmission and generation infrastructure.
These recommendations are aligned with the suggestions given by NERC and are consistent with the RC’s SOL Methodology and the NERC SOL Whitepaper.

36. Next Steps Submit SAR to retire TOP-007-WECC-1
Industry support of POTF recommendation

37. SAR for Retiring TOP-007-WECC-1
POTF created a “crosswalk” for each requirement
Provides a justification for retiring the standard
Describes how the requirements are already addressed elsewhere

38. Questions?